Printer won't turn on, adapter changed, adapter LED still off

Hi to all,

My HP Deskjet 3050 (not 3050A) will not turn on. Seeing that the power adapter LED indicator would not turn on, I bought a new one, but the new adapter LED indicator will not turn on either. And obviously the printer still does not turn on.

What could be the cause? How can it be repaired?

Many thanks!

Jean-François